Hi Sarah. My situation is a little different. I wasn't officially diagnosed until after my son was born 3 years ago, so my diagnosis was "post partum depression". Now everyone finally believes me that I was suffering from depression for probably 20 years.
Since my diagosis is PPD, it was easier to tell more people (mainly b/c I wanted to warn pregnant friends about what to look out for, and hopefully convince them there's no stigma to it).
Basically, I've told my husband, my parents, my doctors, and a few close friends. I haven't told anyone from work.